Dr. Enfcn on CryJlalligation. 
the formation of precious ftones, bafaltes, Sec, 
are all the effects of the famecaufe; and if we 
conjedure that the fetting of metals is a fpecies 
of cryftallization, we fhall hot be wide of the 
truth. This much is certain, that all the femi- 
metals, when broken, difeover a laminated tex¬ 
ture, and in each particular metal thefe lamina 
are always of a given or conftant form. 
That we may, therefore, proceed with due per- 
fpicuity,'.it will be necefifary to take a nearer 
view of the fubjed, and to confider, fhortly, the 
phenomena*attending the cryftallization both of 
fimple and compound bodies. The cryftalliza- 
tion of a fimple cryftallizable body may be 
affeded merely by removing the caufe of its 
fluidity, fince by this means, its component parts 
will have an opportunity of arranging themfelves 
into mafles more or lefs regular and tranfparenr, 
according to the nature of the body, and the law 
of its cryftallization. 
The leaft refledion will ferve to difeover, that 
bodies may be converted from a folid to a fluid 
Hate, in two different ways, viz. either in the 
way of folution, or fufion by heat. 
Of the fir ft, we have endlefs examples from the 
folution of falts in water, and other fluids ; and 
the fecond may be very well illuftrated by the 
procefs of making glafs. * 
* Jn the lx vi vol. of the Phil. Tranf. No. 34, Mr. Keir 
gives an account of glafs forming cryftals when it paffes 
from a fluid to a folid hate by flow degrees. 
In 
